VPHY 101 Study Guide - Final Guide: Endoplasmic Reticulum, Skeletal Muscle, Cardiac Muscle
24 Jan 2022
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GUIDE - Titles
Muscle Physiology
1. Three types of muscle create a wide range of movements.
a. Smooth
b. Skeletal
c. Cardiac
2. Skeletal Muscle
a. Skeletal muscle consists of muscle fibers lying parallel to each other
b. Myosin forms the thick filaments
c. Actin, along with tropomyosin and troponin, forms the thin filaments
3. Molecular Basis of Skeletal Muscle Contraction
a. During contraction, cycles of cross-bridge binding and bending pull the thin filaments
closer together between the stationary thick filaments, causing shortening of the
sarcomeres
b. Power stroke
c. Complete shortening is accomplished by repeated cycles of cross-bridge binding and
bending
d. Calcium is the link between excitation and contraction
i. Spread of the Action Potential Down the T Tubules
ii. Release of Calcium from the Sarcoplasmic Reticulum
iii. ATP-Powered Cross-Bridge Cycling
iv. Removal of calcium is the key to muscle relaxation
1. Rigor Mortis
e. Contractile activity far outlasts the electrical activity that initiated it
4. Skeletal Muscle Mechanics
4. Skeletal Muscle Mechanics
a. Muscle organs are groups of muscle fibers bundled together by connective tissue, often
attached to skeletal elements in antagonistic pairs
b. Contractions of a whole muscle can be of varying strength
c. The number of fibers contracting within a vertebrate muscle depends on the extent of
motor unit recruitment
d. The frequency of stimulation can influence the tension developed by each vertebrate
skeletal muscle fiber
i. Twitch Summation and Tetanus
e. Twitch summation results from a sustained elevation in cytosolic calcium
f. Arthropod muscle tension is controlled by gradation of contraction within a motor unit
g. There is an optimal muscle length at which maximal tension can be developed on a
subsequent contraction
i. At Optimal Length (lo)
ii. At Lengths Greater Than lo
iii. At Lengths Less Than lo
iv. Limitations on Muscle Length
h. Muscle tension is transmitted to skeletal elements as the contractile component
tightens the series-elastic component
i. The two primary types of contraction are isotonic and isometric
j. The velocity of shortening is related to the load
k. Skeletons include endoskeletons, exoskeletons, and hydrostatic skeletons
l. Interactive units of skeletal muscles, tendons, skeletons, and joints form lever systems
m. Elastic storage structures can greatly increase the efficiency and speed of locomotion
5. Skeletal Muscle Metabolism and Fiber Types
a. Muscle fibers have alternate pathways for forming ATP
i. Phosphagens
ii. Oxidative Phosphorylation
b. Fatigue may be of muscle or central origin
c. Increased oxygen consumption is necessary to recover from activity
d. Although muscles can accomplish work, much of the energy is converted to heat
e. There are three types of skeletal muscle fibers, which differ in ATP hydrolysis and
synthesis
i. Fast versus Slow Fibers
ii. Oxidative versus Glycolytic Fibers
iii. Genetic Endowment of Muscle Fiber Types
f. Muscle fibers adapt considerably in response to the demands placed on them
i. Improvement in Oxidative Capacity
ii. Muscle Hypertrophy
iii. Influence of Hormones
iv. Interconversion between Fast Muscle-Fiber Types
v. Muscle Atrophy
vi. Limited Repair of Muscle
6. Adaptations for Flight: Continuous High Power at High Contraction Frequencies
a. Adaptations for Flight: Continuous High Power at High Contraction Frequencies
7. Control of Motor Movement
a. Multiple motor inputs influence vertebrate motor unit output
b. Muscle spindles and the Golgi tendon organs provide afferent information essential for
controlling skeletal muscle activity
i. Muscle Spindle Structure
ii. Stretch Reflex
iii. Coactivation of γ and α Motor Neurons
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